将byte []附加到另一个byte []的末尾

Question

我有两个byte[]长度未知的数组，我只想将一个附加到另一个的末尾，即：

byte[] ciphertext = blah;
byte[] mac = blah;
byte[] out = ciphertext + mac;

我曾尝试使用，arraycopy()但似乎无法使其正常工作。

Answer 1

使用System.arraycopy()，应类似于以下内容：

// create a destination array that is the size of the two arrays
byte[] destination = new byte[ciphertext.length + mac.length];

// copy ciphertext into start of destination (from pos 0, copy ciphertext.length bytes)
System.arraycopy(ciphertext, 0, destination, 0, ciphertext.length);

// copy mac into end of destination (from pos ciphertext.length, copy mac.length bytes)
System.arraycopy(mac, 0, destination, ciphertext.length, mac.length);